Resilient getter supporting arrangement



D. W. HAWKINS March 19, 1963 RESILIENT GETTER SUPPORTING ARRANGEMENT Filed May 19. 1960 INVENTOR:

DARYL W. HAWKINS,

lfi saiome States ice 3,082,346 RESILIENT GETTER SUPPORTING ARRANGEMENT Daryl W. Hawkins, Schenectady, N.Y., assignor to General Electric Company, a corporation of New York Filed May 19, 1960, Ser. No. 30,154 10 Claims. (Cl. 313-180) My invention relates to electric discharge devices and pertains more particularly to a new and improved getter supporting arrangement for use therein.

Some electric discharge devices include cathode structures having a getter arrangement supported thereon in order to enable utilization of the cathode heating element for heating the getter to a temperature at which it will effectively sorb undesired gases in the envelope of the device. One form of such arrangement heretofore employed includes a cup-like cathode member formed of a metal such as nickel having welded to the closed end thereof a thin plate of a highly refractory metal. Bonded to this thin plate is a thin plate of getter material. The intermediate plate is formed of a material which is nonalloying with respect to the materials of the cathode member and getter. At relatively low cathode operating temperatures this arrangement can serve to support the getter material in essentially non-alloying relation to the cathode member and without introducing distortion problems between the joined dissimilar metals.

However, at substantially increased cathode temperatures and under tube operating conditions requiring frequent turning of the device on and off expansion differences between the various elements can result in deformation, such for example, as out-of-roundness of the cathode member which, in turn, can adversely affect the interelectrode spacing between the cathode and a cooperating electrode, such as a grid. Additionally, the thermallycaused stresses sometimes have the effect of tearing either or both the interposed member and the surface of the cathode member on which the getter arrangement is mounted. Still further, at the mentioned elevated temperatures minute perforations in the interposed member, which are sometimes caused by the Welding operation whereby that member is secured to the cathode, often prove large enough to enable the diffusion therethrough of the getter material with resultant undesirable alloying of the materials of the getter and cathode members. This undesirable alloying sometimes is.also made possible by the mentioned tearing of the material caused by high internal stresses due to diiterent expansions.

My invention contemplates the provision of a cathode and getter support arrangement wherein the getter element is supported on a cathode member in desirable high thermal transfer relation and by an interpositioned element in a manner which will avoid undesirable alloying between the elements of the arrangement and will avoid thermally-caused distortion and fracture of the elements.

Accordingly, the primary object of my invention is to provide a new and improved getter supporting arrangement.

Another object of my invention is to provide a new and improved combined cathode and getter supporting arrangement.

Another object of my invention is to provide a new and improved combined cathode and getter supporting arrangemnet including improved means effective for avoiding undesirable alloying of the materials of the getter and cathode elements and for avoiding undesirable thermally-caused distortion and fracture of the elements.

Further objects and advantages of my invention will become apparent as the following description proceeds; features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of my invention I provide a cup-like cathode member including a closed end. Mounted fiat on the end surface of the cathode member is a plate-like support member including a plurality of outwardly extending and expansible projections and having only the outer ends of the eXpansible projections secured to the cathode member. Mounted flat on the surface of the support member and inwardly disposed relative to the projections is a plate-like getter element. The getter element is secured to the support member at only a restricted central portion. Additionally, the material of the support member is essentially non-alloying with respect to the materials of the cathode member and getter element.

For a better understanding of my invention reference may be had to the accompanying drawing in which:

FIGURE 1 is an enlarged partially sectionalized illustration of a cathode and getter arrangement constructed in accordance with an embodiment of my invention; and

FIGURE 2 is an enlarged fragmentary perspective and partially sectionalized view of the structure of FIGURE 1.

Referring to FIGURE 1, there is shown an embodiment of my invention including a cathode structure generally designated 1. The structure 1 can include a cup-like cathode member 2 formed preferably of nickel and mounted on a cathode shield or support member 3. Contained in the cathode member 2 is a suitable heating element 4 which is adapted, when energized, for rendering the outer cylindrical surface of the member 2 emissive. This outer cylindrical surface can be provided with a coating of an electron emissive material or the member 2 can be formed of material adapted for readily emitting electrons when heated. It is to be understood from the outset that while I have shown and described the member 2 as an integral cup-like element it can alternatively be a fabricated member including separately formed and suitably joined side wall and end wall members.

The top or end wall of cathode member 2, as viewed in FIGURE 1, comprises a planar surface 5. Mounted on the surface 5 is a getter support member generally designated 6. As seen in FIGURE 2 also, the getter support member includes a plate-like central support portion 7 which is superposed on the surface 5 of the cathode member. The portion 7 can, from the heat transferring position, be advantageously in contact with the cathode. However, the portion 7 is in no way directly secured to the cathode member.

Included in the support member 6 and extending radially from the portion 7 thereof are a plurality of circumferentially spaced projections 8 which, as seen in FIGURE 2, can advantageously be six in number. The projections 8 are formed as loops which include radially spaced inner and outer leg 9 and'lil, respectively, defining bight portions extending parallel to the longitudinal axis of the cathode member. The inner legs 9 are integral with the rim of the plate-like support portion 7 and the outer legs it? include flat tabs 11. The tabs 11 are generally co-planar with the support portion 7 and are spot welded as shown at 12 to the surface 5 of the cathode member.

Secured to the upper surface of the support portion 7 of the getter supporting member is a plate-like getter element 13. As seen in both FIGURES 1 and 2 the getter element 13 corresponds generally in area and configuration to the support portion 7. Also, the getter element is secured to the supporting portion by a metallic bond indicated at 14 which is restricted to only a relatively small central area of the joined members.

In the arrangement described to this point any thermally-caused distortion between the supporting portion 7 and the getter element 13 is minimized by the restricted central bond 14. Additionally, no thermally-caused distortion can be transmitted between these portions of the getter element and support portion through the radially extending loops because of the construction of the loops which allows for relative expansion and contraction movements of the legs 9 and 1G defining each of the loops. Thus, any expansive or contractive movements of the cathode will not be transmitted to the supporting portion 7 of the getter element 13 because of the expansible con struction of the loops 8. Conversely, if any thermallycaused expansion or contraction of the portion 7 of the supporting member or the getter element '13 should re- I sult, it will not be transmitted to the outer legs 10 and tabs 11 of the supporting member, which tabs are the only portions of the assembly directly secured to the cathode member. Therefore, no distorting stresses will be transmitted to the cathode member and the cathode member will be unaffected.

The getter element 13 is formed preferably of a material selected from the group consisting of titanium, zirconium and alloys thereof, which materials are readily alloyable with nickel of which the cathode member 2 is preferably formed. It is undesirable that alloying of materials occur and, therefore, I have formed the supporting member 6 of materials selected from the group consisting of molybdenum, tungsten, tantalum and alloys thereof; which materials are characterized by generally high thermal conductivity and are essentially non-alloying with respect to both the getter materials and the cathode member material.

Additionally, in my improved structure the only welding between the getter support and cathode members occurs between the tabs 11 on the support member and the cathode member; the tabs are remotely located relative to the getter element. Thus, if any minute perforations in the tabs 11 should result from the welding operation there can be no danger of alloying the getter material and the cathode material by diffusion of the getter material through the weld perforations. Furthermore, inasmuch as my improved structure includes no bonding of substantial planar surfaces there are no resultant high stresses which can cause distortion of elements and tearing of the surfaces of the cathode member or the edge of the interposed getter support portion which would expose the structure to alloying of the getter and cathode materials through the torn edges.

It is to be understood that while I have shown the supporting member 6 as being circular, it can have any desired configuration. For example, it can be rectangular. Additionally, it need not be mounted on a cathode surface. Instead, it can be mounted on any heated surface in a device, such, for example, as the support member 3 in FIGURE 1. Additionally, the support portion of the member 6 need not be planar but can be shaped to conform to the surface upon which the member 6 is mounted.

While I have shown and described a specific embodiment of my invention I do not desire my invention to be limited to the particular form shown and described, and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A getter arrangement for an electric discharge device comprising, a member adapted for being heated during normal operation of the device and including a planar surface portion, a getter support member including an imperforate planar central support portion superposed on said planar surface portion of said first-mentioned member and in heat-transferring engagement therewith, and a plurality of discrete outwardly expansible projections extending from said central portion, only the ends of said projections being secured to said planar surface portion of said first-mentioned member, and a getter element secured to the surface of said support portion opposite said first-mentioned member.

2. A cathode and getter supporting arrangement for an electric discharge device comprising, a cathode member, a getter support member including an imperforate planar central support portion superposed on a surface of said cathode member in heat-transferring engagement therewith, and a plurality of outwardly expansible projections, only the outer ends of said projections being secured to said cathode member, and a getter element secured to the surface of said support central portion of said getter support member opposite said cathode member.

3. A cathode and getter supporting arrangement according to claim 2, wherein said support portion and getter element are superposed plate-like elements that are joined by only a centrally restricted metallic bond.

4. A cathode and getter supporting arrangement according to claim 2, wherein said getter element is formed of a material readily alloyable with the material of said cathode member, and said support member is formed of a material which is essentially non-alloying with respect to the materials of said getter element and said cathode member and serves effectively as a barrier therebetween.

5. A getter support structure according to claim 2, wherein said cathode is formed of nickel, said support member is formed of a material selected from a group consisting of molybdenum, tungsten, tantalum and alloys thereof, and said getter element is formed of a material selected from the group consisting of titanium, zirconium and alloys thereof.

6. A cathode and getter supporting arrangement for electric discharge devices comprising, a cuplike cathode member including a planar end surface, a getter support member including a plate-like central support portion extending parallel to said end surface of said cathode member and having a plurality of peripherally spaced outward projections, said projections comprising loops extending generally transverse the plane of said support portion, only the outer end of said loops being secured to the end surface of said cathode member, a plate-like getter element disposed in the space defined by said projections and bonded to the surface of said support member opposite said cathode member at only a centrally restricted region.

7. A cathode and getter supporting arrangement for electric discharge devices comprising, a cup-like cathode member including a nickel planar end surface and containing a heating element, a molybdenum support memoer including a disc-like central support portion superposed on said end surface of said cathode, said support member including a plurality of circumferentially spaced radial projections comprising loops extending generally parallel to the axis of said cathode member and having radially spaced inner and outer leg portions, the outer leg portions of'said loops including tabs coplanar with said central portion and being the only portions of said support member bonded to said cathode end surface, and a titanium disc disposed in the space defined by said projections and bonded to the surface of said support member opposite said cathode member and at only a central restricted region.

8. A getter structure comprising a getter support member including an imperforate central support portion, a plurality of peripherally spaced projections formed off the rim of said support portion, each of said projections comprising an integral loop extending transverse the plain of said support portion and having an inner leg integral with said support portion and an outer leg radially spaced from said inner leg, and a getter element secured to the surface of said support portion between said loops.

9. A getter support structure comprising a getter supporting member including a plate-like central support portion, a plurality of peripherally spaced projections formed ofi? said support portionfeach said projections being outwardly expansible relative to said support portion, and a plate-like getter element corresponding generally in configuration to said support portion and being joined thereto at only a limited central region.

10. A getter support structure comprising a getter support member including a disc-like support portion, a plurality of circumferentially spaced and radially expansible mounting projections formed 01f the edge of said support portion, a disc-like getter element superposed relative to said support portion and joined thereto at only a limited central region, and said support portion and getter being formed of essentially non-alloying materials.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A GETTER ARRANGEMENT FOR AN ELECTRIC DISCHARGE DEVICE COMPRISING, A MEMBER ADAPTED FOR BEING HEATED DURING NORMAL OPERATION OF THE DEVICE AND INCLUDING A PLANAR SURFACE PORTION, A GETTER SUPPORT MEMBER INCLUDING AN IMPERFORATE PLANAR CENTRAL SUPPORT PORTION SUPERPOSED ON SAID PLANAR SURFACE PORTION OF SAID FIRST-MENTIONED MEMBER AND IN HEAT-TRANSFERRING ENGAGEMENT THEREWITH, AND A PLURALITY OF DISCRETE OUTWARDLY EXPANSIBLE PROJEC- 